Thonet repair options?

Rick sent me an email yesterday asking for some help, and unfortunately I had no idea where to begin. I thought I would put it out to the group to see if someone has any good ideas. He write;

I have some Thonet bent plywood chairs that need to have the back support piece repaired/replaced (the glue joints have 'sprung' loose and you can't lean back anymore). any ideas? I'll pay to have it done well.
Rick, New Orleans

Does anyone know if you can repair that piece, or maybe even buy a new back support?